Extremely inexpensive gps modules

[Paul Theodoropoulos]

On 8/12/18 17:47, Paul Theodoropoulos wrote:
>  be able to learn more after the USB-TTL adapter I ordered arrives, so 
> I can run the ublox uCenter software which is only available on 
> Windows. I'm not going to try taking the lid off.
>
> There's no evidence that the 'battery' (or more likely 'super' cap) on 
> the package actually  is connected to anything. It seems to lose 
> everything on a power-cycle.
Followup. Much probing in uCenter, no configuration will 'take' - set 
stationary mode, survey-in, blah blah - all lost at the next powercycle, 
no evidence that almanac/ephemeris data is saved, so it's a fifteen 
minute slog at each startup. Blech.

Was getting pretty poor performance in the original build on the Pi Zero 
W, so switched the board to an existing RPI 3B+, dramatic improvement:

https://imgur.com/a/H0t8D9n

So, pretty clearly the Pi Zero W, as attractive and tiny and inexpensive 
as it is, is not a great platform for NTP. Well, in absolute terms sure, 
it's an order of magnitude better than relying on getting time only over 
the WAN. But with a base difference in cost of only $25 for an RPi 3 B+, 
it's not worth bothering. Use the Zero W for some other task.

Note, I did apply some of my personal favorite fine-tunings - set up 
realtime partitioning, pin gpsd and ntpd to their own cpu's, but they 
only give tiny, incremental improvements - nothing even visible in these 
graphs.


-- 
Paul Theodoropoulos
www.anastrophe.com

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